Process of treating wood pulp for nitration



Patented Nov. 1, 1932 UNITED STATES ARTHUR HOUGH, or PASSAIC, JOHN ROYeera ;(as-maximums W LLIAM CLELAND LEONHARD, or rassnro, nnyv EnsEYrnocnss or TREATING woonrunrfron iv rnarron No Drawing.

Our invention relates to improvements in the manufacture of nitratedcellulose obtained from the nitration of wood pulp having a tion. Thestrength of the acid may be varied within considerable limits,'say up tobut herein we cover the use of sulfuric acid 7 of below theconcentration used for producing parchmentization, in order that ifdesirable the acid-treated material, if in the form of pulp, maysubsequently be formed into av sheet by any of the conventional methodsor otherwise.

To carry out the invention the wood pulp as such or cellulose as such,in a suitably comminuted condition is subjected to the action of dilutesulfuric acid which may be about 10% H SO and then washed substantiallyfree of acid, and dried to the required extent. The material may then benitrated in the form of substantially segregated fibres or may beconverted into a sheet (most advantageously before the drying step) andsubsequently comminuted to an extent most. adapted to the selectedmethod of nitrating. The whole treatment is best eflected at aboutordinary room temperature, since it is well known that at elevatedtemperatures the cellulose would be partly dextrinized, or convertedinto a somewhat gum-like material. I

For eflecting the nitration, if it is desired to produce nitrocelluloseof about 11% nitrogen content, we may employ an acid mixture of say 60%sulphuric acid, 21% nitric acid and 19% water, (these acids beingfigured on the basis of 100% purity). This temperature of the mixedacids during nitration should be at about C. This produces a nitratedcellulose which is particularly suitable for Application filed January29,'193o;s=iia1 ira-424,440;' I

us'ein making nitrocellulose plastics ofhigh solubility:

An important difference between nitratedv waterleaf made from alphapulp, previously treated with sulphuric acid asldescribefd, and thatmade from the untreated .waterle'af, is the color. of the two-products.If. nitrated waterleafr(previously treated with the acid) bedried anddissolved in-any suitable solvent such as ether-alcohol or acetone andthen a.

film made from it, say, by pouring the fluid on a glass plate-andallowing the solvent to evaporate, the-.resulting film is clearandalmost water white.

If however, nitrated waterleaf made from this pulp, not previouslytreated with acid,

be dissolved in the solvent as in the other case, and a film preparedfrom it, then the resulting film will be yellowish, at any rate it willbe distinctly diiferent,and can readily be distinguished from the other.

'We claim V 1. The process of making a nitrated prodnot which comprisessubjecting wood pulp to the action of sulfuric acid of a strength belowthat which produces dextrination or parchmentization of the cellulosicmaterial, washing the product substantially free of acid, drying, andthereafter nitrating same.

2. A nitrated product resulting from the treatment of disaggregated woodpulp with sulfuric acid, such acid of a strength below that required forparchmentization or dex trination, and subsequently nitrating.

3. In the nitration of alpha wood pulp, the herein described preliminarytreatment of said material, by soaking the same in a sulfuric acid of aconcentration too low toe'fiect parchmentization of the said material,then washing out the acid, whereby said material is rendered especiallysuitable for nitration and nitrating the product.

' 4. In the nitration of wood pulp consisting 5. In the nitration ofWood pulp consisting largely of cellulose, the herein describedpreliminary treatment of said pulp which comprises soaking the pulp incomminuted condition in sulphuric acid of about to about, 391%, Washingout, the acid. and sheeting the. treated pulp and nitratingr the same.

6 In the nitration of Wood pulp consisting largely of cellulose, thehereinv described pre-' liminary treatment of said pulp which comprisessoaking the pulp; in comininuted con; dition in sulfuric acid "of about10%, Washing out the acid and shefifiing; the; treated pulp andnitrating the same.

'Z. The process oimakinga; nitratedi prod-l uct which comprisessubjecting Woodjpulpito thev action of sulfuric acid of about 5% toabout 30% strength, washing the productsubstantially free of acidgdrying, and; there-v aften nitrating same.

8'; A nitratecl' product resulting from the treatment of disaggregatedWOOdi pulp with sulfuric acid:,such: acid of about 5%xto about strength,and subsequently nitrating.

ARTHUR; HOUGH.

JOHN RQLYJ DUFFOZRDL WILLIAM CLELANSD; LEONHARD;

